Various electronic devices are mounted on a motor vehicle as a mobile unit. Therefore, the motor vehicle is provided with a wiring harness for transmitting power from a power source and control signals from a computer to the electronic devices. The wiring harness includes a plurality of electric wires and connectors attached to an end of the wires.
The wire includes an electrically conductive core wire and an electrically insulating coating, which coats the core wire. The wire is a so-called coated wire. A connector includes a terminal fitting and an insulating connector housing. The terminal fitting is made of conductive sheet metal or the like. The connector housing is formed in a box-shape and receives the terminal fitting. The connector is joined to a connector in electronic equipment, thereby the wiring harness supplies necessary electric power and signals to the electronic equipment.
The wire of the wiring harness must be distinguished in terms of the size of the core wire, the material of the coating (concerning with alteration in the materials depending upon heat-resisting property), and a purpose of use. The purpose of use means, for example, an air bag, antilock brake system (ABS), control signal such as speed data, and system in a motor vehicle in which the wire is used, such as a power transmission system.
In order to distinguish the purpose of use (system) as described above, the wire of the wiring harness has been colored to various colors. Upon manufacturing a conventional wire, when the outer circumference of the core wire is extrusion-coated with an insulating synthetic resin, the wire is colored to the desired color by mixing coloring agent having the desired color into the synthetic resin.
As for the wire described above, usually, the conductor is continuously coated with the synthetic resin and a long-sized wire is produced to increase the productivity, and the number of times for changing colors is reduced as much as possible. Accordingly, usually, a long-sized wire having the same color is produced. As for a packing of the wire, usually, the packing is carried out with a large lot and a long-sized product and for example, in a stockroom of a wire company, a wire having a color which meets the demand of a customer is usually sold by the piece. A wiring harness for use in an electric circuit, in which there are many combination of colors, is used in a motor vehicle, appliance, aircraft, and electric machine.
Accordingly, in a conventional wire factory, a great deal of wires is produced per product number and stocked. Then, according to the needs of products using wires such as a wiring harness, the stoked wires are shipped to a factory of a wiring harness or the like. Therefore, in a wire factory or a wiring harness-assembling factory, a wide space is needed to stock a great deal of wires, resulting in that the time-consuming control of wires of various product numbers is inevitably required.
Further, when the wires described above is produced, a pellet of the synthetic resin for constituting the coating of a wire and an additive, such as plasticizer, to be added to the synthetic resin are conveyed from a wire maker to a compounder who mixes the pellet and the additive. The compounder first dissolves, the pellet and the additive, then mixes them and then, cures it before shipping it to the wire maker. In a wire factory, the mixture of the pellet and the additive is dissolved again, then a core wire is extrusion-coated with it. Further, the coating of the wire is crosslinked according to needs, thus the wire is produced.
Accordingly, since it takes a lot of time to produce a wire, that is, to produce a wiring harness, it is not a good way to start producing the wire after receiving an order of a wire or wiring harness. This is a reason why the wire maker produces and stocks a large amount of the wires per their product number prior to receiving an order, while anticipating an order.
A motor vehicle maker receives many different demands from the users. Electronic equipment to be mounted on the motor vehicle is varied depending on the users, resulting in that sizes of wires for use in a wiring harness and the outer color of the wires become various and that an amount of wires of a given product number to be used tends to decrease. Thus, generally, the production of the wires is required to be the production of a small amount per each of various product types.
However, if the wire is produced by the conventional method as described above, since the number of types of the wires to be produced increases, therefore a space for stocking the produced wires increases and the control of the wires becomes further time-consuming work. Moreover, since the amount of the wire of a given product number to be used decreases, period of time for stocking the wire tends to become longer. Thus, according to the conventional process for producing a wire, that is, for producing a wiring harness, the production cost tends to increase, causing increasing in the cost of the wire itself, that is, the cost of the wiring harness itself.
Furthermore, when a wire is crosslinked in the conventional wire factory, various devices for the crosslinking has been used. The device for the crosslinking includes: an enclosed box through which the wire passes; and an irradiation unit to irradiate an electron beam onto the wires which pass through the interior of the box. The box is covered with a material such as copper to prevent the electron beam from leaking out outside.
A plurality of the irradiation units are arranged in the circumferential direction of the wire and irradiate the electron beam onto the coating of the wire for its whole circumference. Thus, the coating of the wire is crosslinked for its whole circumference. A conventional device for the crosslinking tends to become large since it includes a plurality of the irradiation units.